In practice, various techniques are employed in order to solve the problem for providing flight safety of civil aircrafts from missile attacks:
1. The “elimination of missile launch place”, where a locality is guarded and patrolled. However, this technique required great resources and could not guarantee the flight safety because of great area of “risk zone” (zone from which there is a possibility to hit a flying aircraft).
2. The “lowering trail temperature” technique is not effective. Missiles having infrared (IR) seeker heads react to heat energy and are guided to a jet aircraft because of high temperature of its engine and exhaust gases. It is possible to decrease a little an IR heat trail by means of pumping air additionally around an engine exhaust, which could decrease its temperature a little. But even such lowering is very ineffective protection means from modern missiles that find their targets in the case of low temperature of engine.
3. The “strengthening aircraft” technique is restricted in practice use. An exact place of missile hit into an aircraft is unpredictable. Weight and cost of modernization being expected in the case of mounting armour onto a whole aircraft are ultimately high. But when mounting armour only onto critical aircraft assemblies (such as engines, fuel tanks, cockpit, and electronics units), the most part of aircraft will remain still vulnerable for a missile.
4. The “false targets—flashes” technique could “muddle” a missile guiding device. It should be noted that such targets are expensive and danger. On launching they catch fire and discharge a great amount of IR energy, which could “guide a missile to a false trail”. However, pyrotechnic targets could provoke a fire, if they fall down onto the earth prior to be burned out completely.
There are other techniques to protect civil aircrafts from missile with infrared self-guided heads of portable anti-aircraft missile complexes. (See, for example, GB 2309290 A, 23 Jul. 1997; U.S. Pat. No. 5,249,527 A, 5 Oct. 1993; FR 2694804 A1, 18 Feb. 1994; DE 3835887A1, 3 May 1990). The most prospective among them are based on creating special radiation in a range of frequencies corresponding operation frequencies of systems that guide missiles to air targets. The purpose of such actions is often to wreck the process of guiding an infrared seeker head to an aircraft.
The closest in technical essence to the claimed method is a method for protecting aircrafts from missiles provided with seeker heads (see the Russian patent No. 2141094, 17 Aug. 1998). In accordance with said known method, a holographic image of real source radiating electromagnetic waves preferably in the range of visible and infrared spectrum is formed in the space between an aircraft and the most probable direction of possible enemy missile attack. Sources radiating electromagnetic waves at other frequencies corresponding to operating frequencies of various systems for guiding missiles to air targets could also be used as a false target.
However, a state of space between an aircraft and the most probable direction of possible enemy missile attack depends in a great degree on weather condition. This is the reason that prevents to obtain a holographic image of such a quality that would ensure a high reliability of protection in optical interference conditions.
The closest in technical essence to the claimed system is a system of aircraft protection from missile provided with seeker heads, which is intended to perform the aforementioned known method (see the above Russian patent No. 2141094).
The unstable state of space between an aircraft and the most probable direction of possible enemy missile attack, which depends in a great degree on weather conditions, could be again indicated as the reason preventing to obtain a holographic image of such a quality that would ensure a high reliability of protection in optical interference conditions.
At the present time, the probability of using portable anti-aircraft missile complexes against a civil aircraft by terrorists is rather great. The portable anti-aircraft missile complexes employing missiles with infrared seeker heads are simple in use, requires minimal skill in treatment, and are set ready for action in less than three minutes. They are spread widely. There are approximately 500000 units of indicated complexes in the world. And although their most part are under a control of responsible state bodies, these complexes are still available at the black arm market at the price of several tens of thousands of USD. At the present time, portable anti-aircraft missile complexes employing missiles with infrared seeker heads are considered to take a part in an arsenal of some 27 terrorist and underground alignments. Moreover, this armour uses missiles, i.e., air vessels. An action range of many models of this arm is more than 6 km, and using this arm it is possible to hit an aircraft flying at a height of more than 3 km. Hence, a civil aircraft, when flying up or landing, is under the threat of attack from an area of several hundred square kilometers. Thus, the problem of protecting civil aircrafts from the aforementioned arm is of extreme actuality at the present.